Psoas minor muscle

Origin: Tendinous fascia of the quadratus lumborum at the level of the last thoracic vertebrae and on the ventral surface of the last thoracic vertebra and on the first four or five lumbar vertebrae.

Insertion: Arcuate line as far as the iliopectineal eminence.

Action: To steepen the pelvis, or to flex the lumbar part of the vertebral column.

Nerve: Lateral branches of the rami ventrales of the lumbar nerves.

A deep muscle of the lumbar region, the psoas minor connects the ventral surface of the last thoracic vertebrae and the first lumbar vertebrae to the arcuate line as far as the iliopectineal eminence, contributing to pelvic inclination and flexion of the lumbar spine.